#include <stdio.h>

struct animals
{
    char dog;          // m=1, 1+7        
    unsigned long cat; // m=8, 8+0
    short pig;         // m=2, 2
    char fox;          // m=1, 1
} __attribute__((packed)); // M=32

int main(int argc, char const *argv[])
{
    printf("%ld\n", sizeof(struct animals));

    // pig偏移量

    return 0;
}
